Acid disazo dyestuffs and a process for their manufacture



Patented Aug. 13, 1946 UNITED STATES PATENT OFFICE ACID DISAZO DYESTUFFS AND A PROCESS FOR THEIR MANUFACTURE Adolf Krebser, Riehen, near Basel, Switzerland,

assignor to J. R. Geigy A. G., Basel, Switzerland No Drawing. Application June 15, 1942, Serial No. 447,147. In Switzerland July 29, 1941 The dyestuff which constitutes a dark red powder dissolves in water with a yellowish red coloration, in sulfuric acid with a violet coloration and dyes wool from an acid bath in light-fast, bluish-red shades.

According to the process described in the above example the following dyestuffs may be obtained:

- Shade of the acid Example Tetrazo compound irom- Coupling component W001 dyeing 2 4:4'-dimethoxy-3:3-diaminodiphenylsulione 2-amino-8-hyd.roxynaphthalene-(i-sulfonic acid... Red. 3.. 4:4-dianiinodiphenylsulfoxide do Bluish-red.

3 3-diaminodiphenylsu1fone Yellowish-red.

4-dimet -3 5 diaminodiphenylsulfon Bluish-red. 4 4-dichloro-2-2 diaminodiphenylsulfone Blue-red. 3 3'-dimethyl-4 4-diammodiphenylsulfone Red. 3 :3 -dimethyl-4 4-diaminodiphenylsulfoxide o. 4 :4-di.methyl-2: 2-diaminodipheny1sulione Blue-red. 4:4-diaminodiphenylsulfone Bluish-red. 4 :4'-dichloro-3 3-diaminodiphenylsulione Do.

A preferred dyestuff according to the invention,

and that to which the appended claim is particularly directed, is the dyestufi of Example 4.

What I claim is: The acid disazo dyestufi having in the free state the following formula molecules of 2-amino-8-hydroxynaphthalene-6- sulfonic acid.

The new dyestufis possess a surprising good light fastness and a remarkable sea-water fastness.

The present invention is illustrated, but not limited, by the following examples: NH,

Example 1 p I 27.6 parts of 4:4'-dimethyl-3:8-diaminodi- N=N phenyl sulfone are tetrazotised in the usual manner. The tetrazonium solution is then coupled with 47.8 parts of 2-amino-8-hydroxynaphthalene-G-sulfonic acid which has been dissolved neutrally in 200 parts of water and the required quantity of sodium carbonate and again precipitated with hydrochloric acid by acidifying until a Congo-acid reaction has been reached. The coupling takes place slowly, but may be accelerated by heating and adding sodium acetate. When the dyestuff formation is completed, the whole is made neutral to Congo by means of a solution of sodium carbonate, then filtered and dried.

SOaH

85 IIIH:

ADOLF KREBSER. 

